CVE-2026-128342
HIGH
NVD
CVSS Score
7.5
Severity
HIGH
Published
Nov 13, 2026
Vendor
unknown
Description
ExcelJS through 4.4.0 contains a denial of service vulnerability that allows attackers to block the event loop by supplying an unbounded sheetId in xl/workbook.xml. Attackers can provide a workbook with a huge sheetId, making the sparse worksheet array walk stall worksheets, getWorksheet and writeBuffer for seconds.
References
- https://github.com/exceljs/exceljs
- https://github.com/exceljs/exceljs/blob/v4.4.0/lib/doc/workbook.js#L119-L125
- https://github.com/exceljs/exceljs/blob/v4.4.0/lib/doc/workbook.js#L200-L206
- https://github.com/mateocallec/exceljs-hardened/security/advisories/GHSA-9vv6-5g3h-prg5
- https://www.vulncheck.com/advisories/exceljs-through-4.4.0-denial-of-service-via-oversized-worksheet-sheetid